OnJava8-Examples/validating/CountedList.java

// validating/CountedList.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Keeps track of how many of itself are created.
package validating;
import java.util.*;

public class CountedList extends ArrayList<String> {
  private static int counter = 0;
  private int id = counter++;
  public CountedList() {
    System.out.println("CountedList #" + id);
  }
  public int getId() { return id; }
}